What is Blacklist?

According to Talos, roughly 80% of all sent emails are considered spam, which more than justified the need for email blacklisting. 

The practice of identifying and blocking IP addresses associated with spam emails is known as blacklisting. Spam-sending email addresses end up on the blacklist to prevent unwanted messages that clutter email inboxes. 

Each email is sent from a server with an IP address. Referencing the IP address lets blacklisting systems trace an email location and determine whether an IP address is blacklisted or not. Emails on the blacklist are discarded and do not reach the intended recipients.

To avoid getting blacklisted, you need to keep your email list curated. Avoid sending multiple emails to inactive addresses, reduce your sent email volume, and react to spam complaints. If you get a response about how a recipient no longer wishes to receive emails from you, respect their wishes.